A U.S. drone Wednesday fired on an area in northwestern Pakistan , according to two Pakistani intelligence sources and a witness .

Details about what the drone hit and whether there were any casualties were n't immediately available .

Northwestern Pakistan is home to loosely governed tribal areas near the border with Afghanistan , and the area is a base for foreign fighters and a place of refuge for members of the Islamist militant Haqqani movement .

The drone strike comes just days after two brazen attacks on or near Pakistan 's largest airport in the southern Pakistani port city of Karachi .

Earlier Wednesday , the Islamic Movement of Uzbekistan claimed that it carried out one of the attacks -- the weekend airport assault that resulted in an hours-long siege and left 36 people dead , including the assailants .

The claim was made in an e-mail that included pictures that the militant group said were of the 10 attackers .

The militants said the attack was carried out with the Pakistani Taliban , which has confirmed that members of the Islamic Movement of Uzbekistan conducted the Karachi airport attack , Pakistani Taliban commander Abdullah Bahar Mehsud told CNN in a phone conversation .

Mehsud said the pictures in the e-mail claiming responsibility were indeed photos of the 10 attackers . He said the Pakistani Taliban helped coordinate and provided material support in the attack .

Late Sunday night , 10 militants stormed the airport 's cargo area in a siege that left dozens dead .

The Pakistani Taliban also claimed responsibility for that assault , saying the attack was retaliation for the death of former chief Hakimullah Mehsud , who was killed in a U.S. drone strike in November in North Waziristan .

The Uzbek militants have not claimed responsibility for a second attack Tuesday on airport security forces that forced the airport , Pakistan 's largest and busiest , to shut down .

Tuesday 's assault targeted the Airport Security Forces academy near Karachi 's Jinnah International Airport , the airport 's manager told CNN 's Saima Mohsin in Karachi .

Security forces told CNN that an unknown number of gunmen attacked the academy 's entrance and were met with an armed response . The attackers fled , and no one was killed in the attack , officials said .

Once again , the Pakistani Taliban , which is formally known as Tehreek-i-Taliban Pakistan , or TTP , claimed responsibility .

`` This wave of attacks will be continuing in retaliation for the shelling and atrocities of the government , '' spokesman Shahidullah Shahid said by phone Tuesday from an undisclosed location .

Shahid said earlier this week that the Pakistani Taliban would engage `` in a full-out war with the Pakistani state , starting on June 10 . ''

But the airport itself was safe Tuesday , Pakistan 's Civil Aviation Authority said .

'' #Jinnah Airport is safe , #ASF academy is under attack , '' the aviation authority tweeted Tuesday .

The Civil Aviation Authority said flights were temporarily suspended but later resumed Tuesday .

By Tuesday afternoon , the situation was `` under control , '' military spokesman Asim Bajwa said .

`` 3 to 4 terrorists fired near ASF Camp , ran away , '' Bajwa tweeted . `` No breach of fence , no Entry . Chase is on , situation under control . ''

What the Karachi airport attack says about the Pakistani Taliban

Airstrikes killed 15 militants

Hours before the renewed violence in Karachi , the Pakistani military launched a deadly assault targeting nine militant hideouts Tuesday .

At least 15 militants were killed in the airstrikes on Khyber Agency , in tribal areas bordering Afghanistan , the Pakistani military said .

A military spokesman said he could not confirm whether the airstrikes were directly related or in response to the airport violence this week .

But it 's those kinds of strikes that the Pakistani Taliban warned would spur more violence from their end . When the TTP claimed responsibility for Sunday 's airport attack , it called on the government to end airstrikes -- or face more attacks like the Karachi airport terror attack .

Apparently , the TTP followed through with its promise .

History of terror

The Pakistani Taliban has long conducted an insurgency against the Pakistani government .

`` Their primary target is the Pakistani state and its military , '' said Raza Rumi of the Jinnah Institute , a Pakistani think tank .

`` It resents the fact that -LRB- Pakistan -RRB- has an alliance with the West , and it wants Sharia to be imposed in Pakistan . ''

The U.S. Justice Department charged former TTP chief Hakimullah Mehsud in 2010 for his alleged involvement in a 2009 bombing at the United States ' Forward Operating Base Chapman in Khost , Afghanistan . The attack killed seven U.S. citizens , including five CIA officers and a member of Jordanian intelligence .

Hakimullah Mehsud took over from Baitullah Mehsud , a fellow clan member , in 2009 after the latter was killed in a U.S. drone strike . Four years later , Hakimullah Mehsud suffered the same fate .

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Drone fires on area in northwestern Pakistan , sources say

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Islamic Movement of Uzbekistan says it was involved in first Karachi airport attack

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Pakistani Taliban claim responsibility for both attacks in Karachi this week

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The latest assault targeted the Airport Security Forces academy near the airport